1. Field of the Invention
The present invention relates to a corrugated fin type heat exchanger and is suitable for use, particularly, in an air-conditioner for an automobile.
2. Description of the Prior Art
A conventional corrugated fin type heat exchanger is described, for example, in Japanese laid-open utility model publication No. Heisei 2-109178. It discloses that a currugated fin preferably has a height within the range of between 6 mm and 12 mm when taking heat dissipation and resistance to airflow into consideration.
An air conditioning system with such a corrugated fin type heat exchanger tends to be more and more used in motor vehicles. Attempts have been made to improve such a vehicular air conditioning system. This brings about a substantial change in the flow characteristics of air and water. For example, maximum heat exchange efficiency in the conventional air conditioning system, when loaded in a motor vehicle, is slightly changed.
Generally, in a water flow system of a heater core for use in a vehicular air conditioning system, the amount of flowing hot water was determined based on a matching point of the flow resistance in an engine coolant circuit and the characteristic of a pump. FIG. 6 shows the matching point where two curves indicative of the flow resistance and the pump characteristic meet. Also, the flow of air was determined based on a matching point of the flow resistance to air in an air flow system, which is composed of a duct, a heater core, and an evaporator, and the characteristic of a fan. FIG. 7 shows the matching point where two curves indicative of the flow resistance and the fan characteristic meet.
The inventors have considered, through computer simulation, the amount of heat radiation determined by those two curves. Tubes are of the twin type shown in FIG. 8(a) and the single type shown in FIG. 8(b). As a result, it has been found that heat radiation is maximized when a fin has a height within a specific range. Parameter is a core depth D, and the height Hf of the fin is varied. It has also been found that specific range of the fin height Hf is independent of the thickness B of the tubes and the pitch Pf of the fin.